Knife and knife holder assembly

Abstract

A knife and knife holder assembly for use with a sheet material cutting machine includes a replaceable knife with a lower most tip point and a guard and clamp member having a shoe surface engagable with the material being cut to limit the knife's penetration. An adjustment means and a connecting means associated with the guard and clamp member and with the holder allow for quick and easy adjustment of the vertical position of the member on the holder to vary the amount by which the knife protrudes beyond the shoe surface, thereby adjusting its penetration, and also allows quick and easy movement of the member between tightened and loosened conditions relative to the holder, the knife being removable from and replacable in the holder and the member being vertically adjustable in its loosened condition, and the guard and clamp member in the tightened condition of the connecting means being itself fixed to the holder and also holding the knife clamped in a fixed position to the holder.

We claim: 
     
       1. A knife and knife holder assembly for use in a machine for cutting sheet material, said assembly comprising: a knife holder having a lower end with a downwardly facing lower end face and a flat vertical side face intersecting said end face and extending upwardly therefrom,   said knife holder having a vertically extending slot in said side face,   a knife positioned in said slot and having a lower portion extending downwardly beyond said end face of said holder, said lower portion of said knife having a generally downwardly facing cutting edge including a tip point constituting the lowermost extremity of said knife,   a guard and clamp member laterally overlying said knife and said vertical side face of said holder and having a generally downwardly facing shoe surface located vertically between said tip point of said knife and said downwardly facing lower end face of said holder for engaging the top surface of sheet material to be cut,   adjustment means for adjusting the vertical position of said guard and clamp member relative to said holder to adjust the vertical amount by which said tip point is vertically spaced from said shoe surface, and   connecting means for connecting said guard and clamp member to said holder and which connecting means is movable between a loosened condition, at which said member is free for vertical adjustment relative to said holder by said adjustment means and said knife is free for vertical sliding movement relative to said holder for removal from and replacement into said holder, and a tightened condition, at which said member is fixed to said holder and said knife is also fixed to said holder by being clamped between said guard and clamp member and said holder.   
     
     
       2. A knife and knife holder assembly as defined in claim 1 further characterized by said adjustment means including cooperating parts on said holder and on said guard and clamp member defining a vertically elongated slot and a horizontal pin in said slot confining said guard and clamp member to substantially vertical and pivotal movement relative to said holder, said guard and clamp member having an opening of circular cross-section passing horizontally therethrough and defining a first internal bearing surface, a screw passing loosely through said opening in said member and having a horizontal central axis fixed relative to said holder, said screw having a cylindrical bearing portion located in said opening of said member and defining a first external bearing surface, and an eccentric nut received on said screw, said eccentric nut having a circular opening defining a second internal bearing surface complementary to and engaging said external bearing surface of said screw, said nut also having a circular outer surface arranged eccentrically to said second internal bearing surface, said circular outer surface constituting a second external bearing surface complementary to and engaging said first internal bearing surface of said member, and means on said nut which are graspable to rotate said nut relative to said holder about said horizontal axis of said screw, and   said nut having a head located between said guard and clamp member and said head of said screw, said connecting means being said screw, said screw having a head positioned laterally outwardly of said eccentric nut and having a threaded inner end threaded into said holder, said screw being rotatable in one direction or the other about its central axis to move it between said loosened and tightened conditions.   
     
     
       3. A knife and knife holder assembly as defined in claim 2 further characterized by said graspable means on said nut being flats on said head of said nut.   
     
     
       4. A knife and knife holder assembly as defined in claim 2 further characterized by said slot in said side face of said holder being bounded by two vertical walls in planes perpendicular to said side face and said slot also having a flat bottom face parallel to said side face,   said pin of said adjustment means being fixed to said holder and extending horizontally outwardly from said bottom face of said slot beyond said side face of said holder, said pin being spaced upwardly from said lower end face of said holder, and   said elongated slot being formed in a portion of said guard and clamp member and receiving the portion of said pin which extends beyond said side face of said holder.   
     
     
       5. A knife and knife holder assembly as defined in claim 4 further characterized by said knife being of generally rectangular cross-section with inner and outer parallel major side faces, parallel vertically extending side faces, an upper end edge and a sharpened lower end edge, said upper end edge of said knife being engagable with said pin to limit the upward movement of said knife in said slot relative to said holder, and said lower end edge of said knife being inclined so as to intersect one of said side edge faces at said tip point and so as to extend upwardly and laterally away from said tip point to intersection with the other of said side edge faces, said inner major face of said knife being engagable with said bottom face of said slot, said outer major face of said knife being engagable with said guard and clamp member, and said side edge faces of said knife being engagable with said side walls of said slot.   
     
     
       6. A knife and knife holder assembly as defined in claim 5 further characterized by said holder having a vertical central axis about which said holder is rotatable, and said tip point of said knife being located substantially on said central axis.   
     
     
       7. A knife and knife holder assembly as defined in claim 6 further characterized by said guard and clamp member having a vertically extending rib located on its inner face on the opposite side of said screw from said slot which rib is engagable with said side face of said holder to space the remainder of said guard and clamp member slightly from said holder's side face to allow said screw in its said tightened condition to hold said guard and clamp member in tightly clamped relationship with said knife.